Systems and Methods for Purging an Isolation Valve with a Liquid Purge Medium

ABSTRACT

A system and method for purging a bottom slurry circuit isolation valve using hydrocarbons.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application does not assert a priority claim.

TECHNICAL FIELD

The present disclosure relates generally to the purging of isolationvalves. More particularly, the disclosure relates to using hydrocarbonsdistilled in a fractionation tower as a liquid purge media in isolationvalves in a fractionation tower circuit.

BACKGROUND

Fluid catalytic cracking (FCC) is one of the most important conversionprocesses used in petroleum refineries to refine fractions of petroleumcrude oils into more valuable gasoline, olefinic gases, and otherproducts. Cracking of petroleum hydrocarbons was originally done bythermal cracking, which has been almost completely replaced by catalyticcracking. FCC produces byproduct gases that have more carbon-carbondouble bonds (i.e. more olefins), and hence more economic value, thanthose produced by thermal cracking.

Fractionation towers are used throughout a refinery for FCC, coking andother processes. Generally, fractionator towers produce hydrocarbons andbottom slurry as it falls to the bottom as the heaviest of the products.Bottom slurry, which is a mixture of a number of products includingcatalyst particles and unrefined hydrocarbons, is the dirtiest of theproducts and prone to coke in valves and lines if subjected to therequired pressure and temperature. Yet, the slurry is valuable for anumber of reasons, including the hydrocarbons retained. For this reason,bottom slurry is pumped through a circuit from the bottom of thefractionator back into the feed intake for further refining to recoverhydrocarbons.

Isolation valves, which may be any type of valve, control the flow ofbottom slurry through the line. While valves are engineered to preventpotentially destructive process fluids from leaving the line andentering the valve body or bonnets, a purge media under a positivepressure ensures the process fluid does not leave the line. Gasses suchas steam and nitrogen are often used as the purge media. However,purging with gas changes the density of the process fluids and can leadto cavitation in the bottom slurry pumps.

BRIEF SUMMARY

The general purpose of the systems and methods disclosed herein is toimprove isolation valve purging. Specifically, in some embodiments wheremultiple distillation columns or fractionators and slurry pump systemsare present in a refinery, each fractionator has a bottom slurry circuitisolated by an isolation valve. The present invention comprises anisolation valve purge system comprising an FCCU distillationfractionation tower configured to distill hydrocarbons. In someembodiments the fractionation tower has a bottom slurry circuit. In someembodiments the bottom slurry circuit has an isolation valve, withinternal components configured to isolate the flow of process fluidthrough the bottom slurry circuit line. In some embodiments theisolation valve is purged using a liquid purge medium, such as ahydrocarbon (e.g. Light Coking Oil or Light Cycle Oil (LCO), MediumCoking Oil or Medium Cycle Oil (MCO), Heavy Coking Oil or Heavy CycleOil (HCO)) or a combination of hydrocarbons.

Some embodiments comprise a method of purging an isolation valve. Someembodiments comprise distilling oil feedstock into different hydrocarbonweights using a fractionation tower with a bottom slurry circuit. Someembodiments comprise isolating the flow of bottom slurry through thebottom slurry circuit with an isolation valve wherein the isolationvalve is purged using liquid purge medium created in the fractionationtower.

Some embodiments comprise a method for reducing cavitation in apressurized line. Some embodiments comprise purging an isolation valvecontrolling a line with process fluid flowing therethrough with a liquidpurge medium.

Reference throughout this specification to features, advantages, orsimilar language does not imply that all of the features and advantagesthat may be realized with the present disclosure should be or are in anysingle embodiment of the invention. Rather, language referring to thefeatures and advantages is understood to mean that a specific feature,advantage, or characteristic described in connection with an embodimentis included in at least one embodiment of the present disclosure. Thus,discussion of the features and advantages, and similar language,throughout this specification may, but do not necessarily, refer to thesame embodiment, but may refer to every embodiment.

Furthermore, the described features, advantages, and characteristics ofthe invention may be combined in any suitable manner in one or moreembodiments. One skilled in the relevant art will recognize that theinvention may be practiced without one or more of the specific featuresor advantages of a particular embodiment. In other instances, additionalfeatures and advantages may be recognized in certain embodiments thatmay not be present in all embodiments of the invention.

The features and advantages of the present disclosure will become morefully apparent from the following description and appended claims or maybe learned by the practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the advantages and features ofthe invention can be obtained, a more particular description of theinvention briefly described above will be rendered by reference tospecific embodiments thereof which are illustrated in the appendeddrawings. Understanding that these drawings depict only typicalembodiments of the invention and are not therefore to be considered tobe limiting of its scope, the invention will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings in which:

FIG. 1 illustrates a process;

FIGS. 2A-2C illustrate an exemplary FCCU operation and identifiesseveral potential positions for the isolation valve according to someembodiments;

FIGS. 3A-3D illustrate a cutaway of some embodiments of an isolationvalve in a closed position;

FIG. 4 illustrates a cutaway of some embodiments of an isolation valvein an open position;

FIG. 5 illustrates an isolation valve in a partially open or throttledposition according to some embodiments;

FIG. 6 illustrates close-up cut away view of the sealing assembly, biasassembly and liquid chamber;

FIG. 7 illustrates cross-sectional view of floating seat assembly withliquid purge chamber;

FIG. 8 illustrates a cross-sectional view of the bias assembly with andliquid purge chamber;

FIG. 9 illustrates a cross-sectional view of the valve seat with liquidpurge chamber;

FIG. 10 illustrates an alternative cross-sectional view of the valveseat with liquid purge chamber; and

FIG. 11 illustrates an alternative cross-sectional view of the valveseat with liquid purge chamber.

DETAILED DESCRIPTION OF THE INVENTION

The present embodiments of the present disclosure will be bestunderstood by reference to the drawings, wherein like parts aredesignated by like numerals throughout. It will be readily understoodthat the components of the disclosed invention, as generally describedand illustrated in the figures herein, could be arranged and designed ina wide variety of different configurations. Thus, the following moredetailed descriptions of the embodiments of the apparatus, asrepresented in FIGS. 3A-11 are not intended to limit the scope of theinvention, as claimed, but are merely representative of presentembodiments of the invention.

In some embodiments at a refinery or plant, an isolation valve is purgedusing a purge media refined at the refinery, such as hydrocarbonsdistilled in a fractionator. In some embodiments FCC refineries comprisemultiple fractionators. In some embodiments the fractionators distillthe crude feed into component parts of heavy coker oils (HCO), mediumcoker oils (MCO) and light coker oils (LCO), as well as other fuels andgases and the bottom product oil from the main fractionator containingresidual entrained catalyst in Fluid Catalytic Cracking and entrainedcoke particles in de-coking operations, referred to as a slurry oil. Insome embodiments part of that slurry oil is recycled back into the mainfractionator above the entry point of the hot reaction product vapors soas to cool and partially condense the reaction product vapors as theyenter the main fractionator. In some embodiments part of the slurry oilis pumped through a slurry settler. The bottom oil from the slurrysettler contains most of the slurry oil catalyst particles and isrecycled back into the catalyst riser by combining it with the FCCfeedstock oil. The clarified slurry fluid, also called slurry oil ordecant oil, is withdrawn from the top of slurry settler for useelsewhere in the refinery, as a heavy fuel oil blending component, or ascarbon black feedstock. The flow of this slurry oil in the slurrycircuit is controlled by an isolation valve. Slurry oil is the oil mostlikely to leave deposits inside the valve, damaging the valve, thus insome embodiments the HCO, MOC, LCO or a combination of the oils ismaintained under positive pressure greater than the pressuring the lineso as to purge the isolation valve. When used as a purge media a smallamount of the oil enters the process fluid through imperfect sealsbetween the metal on metal surfaces in the valve. However, a percentageof the slurry is made up of hydrocarbons, so the oil is notcontaminating the slurry.

In addition, the addition of hydrocarbons to the slurry preventscavitation in the pumps which pump the slurry through the bottom slurrycircuit. Gas leaking past the valve seats can cause rapid changes ofpressure in a process fluid and lead to the formation of smallvapor-filled cavities in places where the pressure is relatively low.Cavitation is not good for the pumps, and in some instances can damagethe pumps. Using a liquid instead of a gas as a purge media avoids theseproblems.

In some embodiments the purge liquid comprises coker oil, cycle oil orHCO, MCO or LCO, or a combination of these fluids. When HCO, MCO, andLCO are used the positive purge system conditions ie pressures andtemperatures, must be controlled to avoid coking in the valve body andbonnet. The invention contemplates liquid purge medium that may comprisethe hydrocarbons LCO, MCO and HCO, and liquid purge mediums can be usedinterchangeably in the system. As a result, the liquid purge mediumcomprises fractionator hydrocarbons.

In the following description, numerous references will be made toprocessing equipment such as isolation valve, gate, seat, body, bonnet,line, fractionator, bottom slurry circuit, but these items are not shownin detail in the figures. However, it should be understood that one ofordinary skill in the art and in possession of this disclosure, wouldreadily understand how the present disclosure and the structures can beincorporated.

Detailed references will now be made to the embodiments of the disclosedinvention, examples of which are illustrated in FIGS. 3A-11 whichillustrate various views of a valve with liquid media purge ports inaccordance with one or more embodiments of the invention.

General Discussion on the FCC Process

FCC process involves extreme pressures and temperatures. Isolationvalves used in FCC plants include internal components, which aremaintain the valve seal through the extreme temperatures and pressures.

Some FCC processes are shown in FIGS. 2A-2C which illustrate exemplaryFCC operation, highlighting various lines utilized to convey matter,including gases, liquids and solids from one location to anotherthroughout the operation. There are two different configurations for anFCC unit: the “stacked” type where the reactor and the catalystregenerator are contained in two separate vessels, with the reactorabove the regenerator. There is a skirt between these vessels allowingthe regenerator off-gas piping to connect to the top of the regeneratorvessel. And the “side-by-side” type where the reactor and catalystregenerator are in two separate vessels. The stacked configurationoccupies less physical space of the refinery area.

The reactor and regenerator are considered to be the heart of the fluidcatalytic cracking unit. The schematic flow diagram of a typical modernFCC unit in FIG. 2A is based upon the “side-by-side” configuration. Thepreheated high-boiling petroleum feedstock (at about 315 to 430° C.)consisting of long-chain hydrocarbon molecules is combined with recycleslurry oil from the bottom of the distillation column and injected intothe catalyst riser where it is vaporized and cracked into smallermolecules of vapor by contact and mixing with the very hot powderedcatalyst from the regenerator. All of the cracking reactions take placein the catalyst riser within a period of 2-4 seconds. The hydrocarbonvapors “fluidize” the powdered catalyst and the mixture of hydrocarbonvapors and catalyst flows upward to enter the reactor at a temperatureof about 535° C. and a pressure of about 1.72 bar.

The reactor is a vessel in which the cracked product vapors are: (a)separated from the spent catalyst by flowing through a set of two-stagecyclones within the reactor and (b) the spent catalyst flows downwardthrough a steam stripping section to remove any hydrocarbon vaporsbefore the spent catalyst returns to the catalyst regenerator. The flowof spent catalyst to the regenerator is regulated by a slide valve inthe spent catalyst line.

Since the cracking reactions produce some carbonaceous material(referred to as catalyst coke) that deposits on the catalyst and veryquickly reduces the catalyst reactivity, the catalyst is regenerated byburning off the deposited coke with air blown into the regenerator. Theregenerator operates at a temperature of about 715° C. and a pressure ofabout 2.41 bar, hence the regenerator operates at about 0.7 bar higherpressure than the reactor. The combustion of the coke is exothermic andit produces a large amount of heat that is partially absorbed by theregenerated catalyst and provides the heat required for the vaporizationof the feedstock and the endothermic cracking reactions that take placein the catalyst riser.

The hot catalyst (at about 715° C.) leaving the regenerator flows into acatalyst withdrawal well where any entrained combustion flue gases areallowed to escape and flow back into the upper part to the regenerator.The flow of regenerated catalyst to the feedstock injection point belowthe catalyst riser is regulated by a slide valve in the regeneratedcatalyst line. The hot flue gas exits the regenerator after passingthrough multiple sets of two-stage cyclones that remove entrainedcatalyst from the flue gas.

The amount of catalyst circulating between the regenerator and thereactor amounts to about 5 kg per kg of feedstock, which is equivalentto about 4.66 kg per liter of feedstock. Thus, an FCC unit processing75,000 barrels per day (11,900 m3/d) will circulate about 55,900 tonsper day of catalyst.

The reaction product vapors (at 535° C. and a pressure of 1.72 bar) flowfrom the top of the reactor to the bottom section of the main column(commonly referred to as the main fractionator where feed splittingtakes place) where they are distilled into the FCC end products ofcracked petroleum naphtha, fuel oil, and offgas. After furtherprocessing for removal of sulfur compounds, the cracked naphtha becomesa high-octane component of the refinery's blended gasolines.

The main fractionator offgas is sent to what is called a gas recoveryunit where it is separated into butanes and butylenes, propane andpropylene, and lower molecular weight gases (hydrogen, methane, ethyleneand ethane). Some FCC gas recovery units may also separate out some ofthe ethane and ethylene.

Although the schematic flow diagram FIG. 2A depicts the mainfractionator as having only one sidecut stripper and one fuel oilproduct, many FCC main fractionators have two sidecut strippers andproduce a light fuel oil and a heavy fuel oil. Likewise, many FCC mainfractionators produce a light cracked naphtha and a heavy crackednaphtha. The terminology light and heavy in this context refers to theproduct boiling ranges, with light products having a lower boiling rangethan heavy products.

The bottom product oil from the main fractionator contains residualcatalyst particles which were not completely removed by the cyclones inthe top of the reactor. For that reason, the bottom product oil isreferred to as a slurry oil. Part of that slurry oil is recycled backinto the main fractionator above the entry point of the hot reactionproduct vapors so as to cool and partially condense the reaction productvapors as they enter the main fractionator. The remainder of the slurryoil is pumped through a slurry settler. The bottom oil from the slurrysettler contains most of the slurry oil catalyst particles and isrecycled back into the catalyst riser by combining it with the FCCfeedstock oil. The clarified slurry oil or decant oil is withdrawn fromthe top of slurry settler for use elsewhere in the refinery, as a heavyfuel oil blending component, or as carbon black feedstock.

Depending on the choice of FCC design, the combustion in the regeneratorof the coke on the spent catalyst may or may not be complete combustionto carbon dioxide CO₂. The combustion air flow is controlled so as toprovide the desired ratio of carbon monoxide (CO) to carbon dioxide foreach specific FCC design.

In the design shown in FIG. 1, the coke has only been partiallycombusted to CO₂. The combustion flue gas (containing CO and CO₂) at715° C. and at a pressure of 2.41 bar is routed through a secondarycatalyst separator containing designed to remove 70 to 90 percent of theparticulates in the flue gas leaving the regenerator. This is requiredto prevent erosion damage to the blades in the turbo-expander that theflue gas is next routed through.

The expansion of flue gas through a turbo-expander provides sufficientpower to drive the regenerator's combustion air compressor. Theelectrical motor-generator can consume or produce electrical power. Ifthe expansion of the flue gas does not provide enough power to drive theair compressor, the electric motor/generator provides the neededadditional power. If the flue gas expansion provides more power thanneeded to drive the air compressor, then the electric motor/generatorconverts the excess power into electric power and exports it to therefinery's electrical system.

The expanded flue gas is then routed through a steam-generating boiler(referred to as a CO boiler) where the carbon monoxide in the flue gasis burned as fuel to provide steam for use in the refinery as well as tocomply with any applicable environmental regulatory limits on carbonmonoxide emissions.

The flue gas is finally processed through an electrostatic precipitator(ESP) to remove residual particulate matter to comply with anyapplicable environmental regulations regarding particulate emissions.The ESP removes particulates in the size range of 2 to 20 μm from theflue gas. Particulate filter systems, known as Fourth Stage Separators(FSS) are sometimes required to meet particulate emission limits. Thesecan replace the ESP when particulate emissions are the only concern.

The steam turbine in the flue gas processing system (shown in the abovediagram) is used to drive the regenerator's combustion air compressorduring start-ups of the FCC unit until there is sufficient combustionflue gas to take over that task.

The fluid catalytic cracking process breaks large hydrocarbons by theirconversion to carbocations, which undergo myriad rearrangements breakinghigh boiling, straight-chain alkane (paraffin) hydrocarbons into smallerstraight-chain alkanes as well as branched-chain alkanes, branchedalkenes (olefins) and cycloalkanes (naphthenes). The breaking of thelarge hydrocarbon molecules into smaller molecules is more technicallyreferred to by organic chemists as scission of the carbon-to-carbonbonds. Some of the smaller alkanes are then broken and converted intoeven smaller alkenes and branched alkenes such as the gases ethylene,propylene, butylenes, and isobutylenes. Those olefinic gases arevaluable for use as petrochemical feedstocks. The propylene, butyleneand isobutylene are also valuable feedstocks for certain petroleumrefining processes that convert them into high-octane gasoline blendingcomponents. The cycloalkanes (naphthenes) formed by the initial breakupof the large molecules are further converted to aromatics such asbenzene, toluene, and xylenes, which boil in the gasoline boiling rangeand have much higher octane ratings than alkanes. In the crackingprocess carbon is also produced which gets deposited on the catalyst(catalyst coke).

In particular FIGS. 2B-2C illustrate some of the locations where variousembodiments of the isolation valves of the present invention may beutilized. Some embodiments of the valve 14 may be connected to any lineor to a slurry circuit. In some embodiments hydrocarbons from the FCCUare routed into the functional space of an isolation valve, such as thebonnet under a positive pressure greater than the process media, such asa slurry. This is under positive pressure so as to prevent the processmedia from entering the valve housing. In some embodiments where thehydrocarbon purge media is used to purge the slurry circuit isolationvalve mixes, the refined hydrocarbon purge media mixes with the processmedia where it is then returned to the fractionation tower fordistillation.

The feedstock to FCC is usually that portion of the crude oil that hasan initial boiling point of 340° C. (644° F.) or higher at atmosphericpressure and an average molecular weight ranging from about 200 to 600or higher. This portion of crude oil is often referred to as heavy gasoil or vacuum gas oil (HVGO). In the FCC process, the feedstock isheated to a high temperature and moderate pressure, and brought intocontact with a hot, powdered catalyst. The catalyst breaks thelong-chain molecules of the high-boiling hydrocarbon liquids into muchshorter molecules, which are collected as a vapor.

Fractionation towers also known as, distillation columns orfractionators and isolation valves are used throughout refineries andchemical plants. The fractionation tower distills a chemical mixtureinto its component parts, or fractions, based on the differences involatilities. Often fractionators have outlets at intervals up thecolumn so that multiple products having different boiling ranges may bewithdrawn from a column distilling a multi-component feed stream. The“lightest” products with the lowest boiling points exit from the top ofthe columns and the “heaviest” products with the highest boiling pointsexit from the bottom.

Fluid catalytic cracking (FCC) is one of the most important conversionprocesses used in petroleum refineries. It is widely used to convert thehigh-boiling, high-molecular weight hydrocarbon fractions of petroleumcrude oils into more valuable gasoline, olefinic gases, and otherproducts. Cracking of petroleum hydrocarbons uses a catalyst because itproduces more gasoline with a higher octane rating. It also producesbyproduct gases that have more carbon-carbon double bonds (i.e. moreolefins), and hence more economic value.

The feedstock to FCC is usually that portion of the crude oil that hasan initial boiling point of 340° C. (644° F.) or higher at atmosphericpressure and an average molecular weight ranging from about 200 to 600or higher. This portion of crude oil is often referred to as heavy gasoil or vacuum gas oil (HVGO). In the FCC process, the feedstock isheated to a high temperature and moderate pressure, and brought intocontact with a hot, powdered catalyst. The catalyst breaks thelong-chain molecules of the high-boiling hydrocarbon liquids into muchshorter molecules, which are collected as a vapor.

The feed stock passes through a reactor and into a fractionator wherefeed splitting takes place. In the fractionator the feed stock isdistilled into the FCC end products of cracked petroleum naphtha, fueloil, and offgas. After further processing for removal of sulfurcompounds, the cracked naphtha becomes a high-octane componentgasolines.

FCC main fractionators often have two sidecut strippers and produce alight fuel oil and a heavy fuel oil. Likewise, many FCC mainfractionators produce a light cracked naphtha and a heavy crackednaphtha. The terminology light and heavy in this context refers to theproduct boiling ranges, with light products having a lower boiling rangethan heavy products.

The bottom product oil from the main fractionator contains residualcatalyst particles. For that reason, the bottom product oil is referredto as a slurry oil. Part of the slurry oil is pumped through a slurrysettler. The bottom oil from the slurry settler contains most of theslurry oil catalyst particles and is recycled back into the catalystriser by combining it with the FCC feedstock oil. The clarified slurryoil or decant oil is withdrawn from the top of slurry settler for useelsewhere in the refinery, as a heavy fuel oil blending component, ascarbon black feedstock, or in some cases the slurry oil is pumpedthrough a bottom circuit for use in heat recovery or steam creationusing a slurry bottom circuit.

Isolation valves are used in fluid handling systems to stop the flow ofprocess media to a given location. Isolation valves can also be used toprovide flow logic (selecting one flow path versus another), and toconnect external equipment to a system. A valve is classified as anisolation valve because of its intended function in a system, notbecause of the type of the valve itself. Therefore, many different typesof valves can be classified as isolation valves. Isolation valves musteffectively stop the passage of fluids. Gate valves, ball valves, plugvalves, globe valves and butterfly valves may be considered to providetight and effective shut-off when the valve trim, or internalmechanisms, create the necessary seal.

Embodiments of an Isolation Valve

The present disclosure may be utilized in association with isolationvalves, such as those described in U.S. patent application Ser. Nos.12/848,013 and 16/403,039 which are incorporated herein by reference.The invention may be utilized on bottom slurry circuits, such as thoseshown in FIGS. 2B-2C, along with any isolation valve used in an FCCU.One ordinarily skilled in the art will recognize that the invention asexplained and described herein use of fractionator hydrocarbons as apurge media for isolation valves may also be designed and used for othersystems as well.

The present disclosure describes a valve purge media system and methodfor purging isolation valves such as those used in a bottom slurrycircuit systems and methods may be utilized within other criticalservice applications, such as inlet feed line isolation, fractionatorisolation, and back warming.

The present invention may be utilized to control the flow of processmedia, matter, including slurry fluid, any fluids, solids and/or gases,at any point in the isolation valve operation so as to prevent thesefrom entering the valve trim eg bonnet, actuator, seat, seal andpreventing proper operation. Additionally, one ordinarily skilled in theart will recognize that the valve as explained and described herein mayalso be designed and used in other environments where controlling themovement of matter, including fluids, solids and/or gases, is desirable.

Examples of isolation valves, and related internal trim is shown inFIGS. 3-11. The specification describes a valve system and method forisolating the flow of a substance in the line. As the present inventionis especially adapted to isolation valves used to isolation bottomslurry circuit. It is foreseeable however, that the present inventionmay be adapted to be an integral part of other manufacturing processesproducing various elements, and such processes should thus be consideredwithin the scope of this application. Prior to reciting the specifics ofthe present invention, it should be noted that the present inventionsystem and method is designed to have or possess significant functional,utility, and safety advantages over prior related designs and systems.

Some embodiments of the valve system may comprise a seat system forisolating the flow of slurry oil through a line from the bottom of thefractionator tower.

Some embodiments comprise: a) an valve coupled to a line in the FCCUoperation wherein the line may be an outlet slurry oil line, and a seatsystem; and b) a structure for actuating the valve closure.

Some embodiments may comprise at least one bonnet. Some embodiments maycomprise an upper and lower bonnet coupled to a main body, wherein thebonnet may be removed in order to replace valve parts without separatingthe main body from the line. Some embodiments may comprise one or moreplates located inside a bonnet, wherein the plate(s) comprise a planarsurface that may contact one or more surfaces on the blind.

Some embodiments of the system may be structured to isolate gases andhot liquids particularly those utilized in the FCCU operations. Someembodiments are structured to provide the benefit of allowing forreliable, extended flow isolation without decreased performance. In someembodiments, maintained high valve performance over extended periods oftime is enhanced by features of the invention including purging thevalve with LCO, MCO or HCO to maintain proper contact between the seatsand blind which acts to remove any debris from the internal component ofthe valve. In prior art systems the likelihood of coking up or oiling uprequired frequent rebuilds and therefore removal of valves from a line.

In some embodiments, the system is configured to purge with hydrocarbonthe main body of the valve, an upper and lower bonnet, each of which maybe independently removed to replace valve parts without separating themain body from the line. Within the bonnets 30 of some embodiments theremay be at least one plate 52 located in opposition to one another whichallow the blind 4 to maintain surface contact with the plate(s). Thepositive pressure of the hydrocarbon purge along with the plate/blind4/52 system located within the bonnets 30 prevent the escape of matter,such as slurry oil, from a line into the bonnet 30. Accordingly, someembodiments prevent exposure of the internal elements of the valvesystem 14 to matter traveling through the line. Consequently, theinternal components of a valve system 14 may remain clean and free fromdebris and build up.

Some embodiments purge a structure for supporting a valve closure 4comprising seat support system 50 with a liquid purge medium. A seatsupport system 50 may comprise an arrangement or configuration of seatsdepending upon the type of valve. In some embodiments the structure forsupporting the valve closure 4 comprise a seat support system 50, whichcomprises a first seat and a second 58, 60 existing on either side ofthe valve closure 4, wherein the first seat 58 and the second seat 60may be independent from one another. In some embodiments, the first seat58 and the second seat 60 may be a pressurized seat cartridge. The firstand second seats 58, 60 may comprise of either a static or a dynamicnature, such that one may be static and the other dynamic, both dynamic,or both static. Alternatively, the seat support system 50 may compriseof a single seat situated or disposed between the main body 16 of thevalve 14 and the valve closure 4. In this configuration, this singleseat applies continuous force to the valve closure throughout itsoscillation. In single seat systems the single seat may be dynamic or itmay be static depending upon the type of valve and the needs of thesystem specification and any other contributing factors.

Embodiments of the valve system comprise a liquid purge system whereinrefined hydrocarbons HCO, MCO or LCO from the fractionation tower arepumped to one or more isolation valves for use in the isolation valve asthe liquid purge media. In some embodiments the liquid purge system mayutilize a line to pull refined hydrocarbons from the fractionator to thebottom slurry circuit isolation valve for use as a liquid purge media.In some embodiments the liquid purge media is maintained at a positivepressure, or a pressure greater than the pressure in the line, so as tocontinually pump hydrocarbons into the line and prevent the processmedia, such as slurry oil, from entering the valve seat, bonnets, orother internal components. The pressure within the purge fluid system ismaintained by using a fluid that is at a pressure greater than theprocess media in the valve.

Some embodiments of the liquid purge media system may comprise aninternal gas/liquid containment system that provides or maintainsisolation of the fluid including gas within the system. The internalfluid containment system may comprise a metal-to-metal contact sealdescribed herein as well as a unique component configuration existingwithin the bonnets 30 of the valves 14. The liquid purge mediummaintained at a positive pressure forced hydrocarbons through themetal-to-metal contact seals, to the extend fluid can pass, to preventprocess fluid from passing the other way through into the valve'sinternal components.

In some embodiments the pumps pumping the liquid purge media to theisolation valve will be turned off when the internal componentsincluding the seat systems 50, seats and blind 4 may be inspected,repaired and/or replaced without detaching the main body 16 of the valvefrom the line.

In some embodiments the valve system 14 comprises a liquid-purged bodywhere the purge media is maintained at a temperature that regulates thevalve body temperature, and that may be structured to create a barrieragainst gas, fluid, and solid migration. The purge elements of theseembodiments prevent the movement of matter into the upper and lowerbonnets 30 from the line. Accordingly, the internal components of someembodiments do not become encumbered by coke deposits or build up. Theinternal components require significantly less repair and replacement.Accordingly, some embodiments of the valve operate reliably for extendedperiods of time without decreased performance.

Some embodiments are structured mechanically to work cooperatively withthe liquid purge media by oscillating under conditions where valve gate4 is maintained in a partially opened or throttled position. In someembodiments the internal components of the bonnet 30 prevent thebuild-up of oil, coke, or debris inside the bonnet 30. Because some ofthe embodiments have liquid purge fluid under positive pressure theinternal components of the valve system 14 are not exposed to slurryoil, coke, and/or other build up while the valve 14 is maintained in apartially opened condition. For example, some embodiments of the valvesystem 14 utilize a liquid purge system which creates a positivepressure inside of the bonnet 30 forcing the contents of a line toremain inline and prevent the contents of the line from moving into theinternal components of the valve 14.

In some embodiments, there may be additional mechanical features whichoperate cooperatively with the liquid purge media to allow the valve tobe maintained in a partially opened position without compromising theperformance of the valve over extended periods of time. For example, insome embodiments the seat system 50 maintains continuous contact withthe gate 4. The continuous contact in some embodiments, shearsaccumulated coke and/or other debris preventing the accumulated materialfrom building up upon the valve 14 itself and from falling into thevarious internal components of the valve system 14. Some embodimentsutilize a system, which is located inside the bonnet 30, which maintaincontact with the gate 4 of the valve 14 while the gate 4 moves throughthe open and closed positions. In some embodiments the bonnet 30,preferably the lower bonnet 34 of the valve 14, contains one or moreplates 52 which opposably face each other and are biased against thesurface of the gate 4 present within the lower bonnet 34. In someembodiments springs 54 are coiled and biased against the lower bonnet 34to lie between bonnet 30 and plate 4. Accordingly, the spring system 56of some embodiments press the plate 56 located in the lower bonnet 34against the surface of the gate 4. The liquid purge media along with theplate system located in the bonnet system 30 prevents the movement ofgases, fluids, or solid matter from the line into the bonnet 30.Accordingly, the combination of the liquid purge media system and platesystem prevents the contents of the line from coming into contact withthe internal elements of the gate system 14.

Turning to the Figures of the present invention and a more detailedanalysis of some of the embodiments of the invention, FIG. 1 depicts,generally, a petroleum manufacturing and refinery process with an FCCUhaving several elements and systems present. Lighter fractions, steamand gases are released from the online coke vessel through the vaporline 2 a and 2 b.

FIG. 3A-3D depicts an embodiment of an isolation valve in an openposition. In some embodiments, the valve as depicted may be connectedone or more of the above described positions (see FIG. 2). Each of FIGS.3A, 3B, 3C and 3D illustrate different embodiments of valves 14.

The valve depicted in FIGS. 3-11 are an embodiment of isolation valves,however it is intended that valve 14 may comprise a variety of valvetypes, and a variety of different elements. The seat system 50 (e.g.,the dual, metal seat surfaces in some embodiments), the bonnet interior36, and all internal parts are fully protected and isolated from anymatter flowing through a line while the valve is in the fully open,fully closed (see FIG. 4) or partially opened (see FIG. 5) positions.Preferably, the materials used in the construction of sealing parts areresistant to corrosion and are designed for exceptionally highmetal-to-metal cycle duty. The seals of the valve 14 are designed tocleanly break the bond between the coke and the exposed surface of thevalve closure at each stroke and the coke is prevented from entering theinternal components by the liquid purge media. The total thrust requiredfor this action combined with the thrust required to overcome seatingfriction and inertia is carefully calculated and is accomplished byactuating the valve closure 4, thus causing it to relocate or transitionfrom a closed to an open position.

In some embodiments part of the liquid slurry is returned to the FCCU inan FCC process to recover hydrocarbons from the liquid slurry. A liquidpurge media is used to purge the isolation valve of any process fluid,such as bottom slurry to prevent the process fluid from entering thevalve body or bonnets. In some embodiments a check valve is used tomaintain a pressure of greater than 10 psi in the system. Using liquidpurge medium provides added benefits over traditional steam or nitrogen.First, liquid purge medium is produced during the distillation process;in contrast, steam or nitrogen must be manufactured. Liquid slurrycreated downline is often pressurized in the process. Any portion of thehydrocarbon purge media injected into the liquid slurry while purgingthe isolation valve can be recycled back into the fractionator 11 abovethe entry point of the hot reaction product vapors so as to cool andpartially condense the reaction product vapors as they enter the cokerfractionator. The remainder of the liquid slurry is pumped through aslurry settler. The bottom oil from the slurry settler contains most ofthe liquid slurry catalyst particles in FCCU process and is recycledback into the catalyst riser by combining it with the FCC feedstock oil.FIG. 2A illustrates an exemplary operation, highlighting various linesutilized to convey matter, including gases, liquids and solids from onelocation to another throughout the operation. In particular FIG. 2Aillustrates some of the locations where various embodiments of theisolation valve of the present invention may be utilized. Someembodiments of the valve 14 may be connected to any line or to a cokedrum. Examples of some positions where embodiments of a valve may beutilized include cutting-water valve 70, overhead vapor valve 71A/71B,blowdown isolation valve 72A/72B, module isolation valve 79,back-warming isolation valve 80, fractionator isolation valve 10, drumbypass isolation valve 78, heater charge pump discharge isolation valve82A/82B, inlet isolation valve 26, switch manifold isolation valve 73,pre-heat warm up isolation valve 74A/74B, quench water isolation valve75, steam isolation valve 76, and drain-to-pit isolation valve 77A/77B.

FIG. 3A-3D depicts an embodiment of the valve system in a closedposition. The depicted valve system 14 is structured to be coupled to aline or coke drum to a flange. In some embodiments, the valve asdepicted may be connected one or more of the above described positionsin the delayed coker unit operation (see FIG. 2A). Each of FIGS. 3A, 3B,3C and 3D illustrate different embodiments of valves 14.

The valve depicted in FIGS. 3-11 are an embodiment of valves of thepresent invention, however it is intended that valve 14 may comprise avariety of valve types, and a variety of different elements.

FIGS. 3-13 illustrate various views of valve 14, according to variousembodiments. The depicted valve 14 comprises a main body 16 coupled toupper and lower bonnets 33 and 34, each comprising lower chambers 35 andupper chamber 36, respectively. Main body 16 comprises a first flangeportion 40 having an opening or port 42 therein, and a second flangeportion 44 having an opening or port 46 therein. Main body 16 couples 26to a complimentary flange portion and associated opening or port of aline 2 or coke drum 18 and 22, such that each opening is concentricand/or aligned with one another.

The depicted isolation valve 14 further comprises a valve closure in theform of a sliding blind or gate 4 having an aperture therein that iscapable of aligning with openings 42 and 46 in an open position. Valveclosure 4 slides back and forth in a linear, bi-directional mannerbetween means for supporting a valve closure, shown in this exemplaryembodiment as seat support system 50. Seat support system 50 maycomprise any type of seating arrangement, including dual, independentseats, wherein the seats are both static, both dynamic, and acombination of these. Seat support system 50 may alternatively comprisea single seat in support of valve closure 4, wherein the seat maycomprise a static or dynamic seat.

In one embodiment it is preferable that a continuous contact seal becreated between valve closure 4 and seat support system 50, such thatduring the back and forth sliding or rotation of valve closure 4 from anopen position, to a semi-opened position, and finally to a closedposition, with respect to the line, the created contact seal is neverbroken or breached, but its integrity is maintained at all times. Thiscontinuous contact seal is preferably a metal-to-metal contact seal thatperforms several functions and has several advantages and operatescooperatively with the liquid purge media described herein. For example,the contact seal creates, or at least contributes to, valve 14isolation, wherein an isolated environment is provided, such that nomaterial is allowed to escape outside the sealed area and into thebonnets 30 or other parts of the valve 14, the area outside the valve,or other areas. Various liquid purge systems and containment systems mayalso function to regulate pressure within the isolation valve 14, tocontain the material within designated areas, and to maintain valveisolation. As another example, the continuous contact seal may help tokeep various components of the isolation valve clean and free of theproduct material as these materials are not allowed beyond the areapurged by the liquid purge. As another example, as a result of the loadexerted upon valve closure 4 and resulting tight tolerances existingbetween valve closure 4 and first and second seats and the rotation ofvalve closure between first and second seats 58, 60 causes a burnishingand polishing effect to occur.

In some embodiments, seat support system 50 comprise first and secondseats 58, 60 as well as valve closure 4 may be made of metal, thusproviding a metal to metal contact or metal to metal seal, or otherwisereferred to as metal to metal seating of valve closure 4. The metal tometal seating increases the durability of the system as there are nonon-metal parts, such as vinyl or rubber, used to seal the seats tovalve closure 4. Metal-to-metal seating allows the system to achieve ahigher consistency of sealing, while at the same time providing extendedwear and durability. In addition, the metal-to-metal sealing allows thesystem 14, and specifically the sealing within the system, to befine-tuned as needed. Each metal-to-metal contact seal in the valve bodycan be supported

As the valve closure 4 is actuated and rotated from a closed position toan open position, the contact seal existing between the surface of valveclosure 4 and the surface of means for supporting a valve closurefunctions to break up or shear the manufactured coke that hasaccumulated on or near the surface of valve closure 4.

Referring now to FIGS. 6-11 which disclose an alternative embodiment ofa valve, such as a floating seat plate configured to isolate processfluid from entering the valve body purged by a liquid purge medium. Insome embodiments separating the seat 23 from the floating seat plate 23improves and simplifies manufacturing by requiring the smaller floatingseat plate be ground flat instead of the combined seat plate 23 and seat23. In some embodiments the floating seat plate 23 improves thedistribution of loads on the seat. The improved load distribution isaccomplished in part by the isolation of the seat plate 23 from the seat23. Heat from processing causes the equipment, including the seat 23,gate 11 and the floating seat plate 23 to thermally expand and changeshape. In addition, the pressurized drum challenges the seal between theseat 23, gate 11 and the seat plate In some embodiments the floatingseat plate 23 isolates the pressure on the seat 23 so as to allow fewerleaks because the seat is not influenced by the seat attachment. Leaksare further reduced by the liquid purge medium under positive pressureso the reside cannot enter between the seals. In addition, in someembodiments the at least partially independent movement by the floatingseat plate allows the seat 23 to partially isolate the pressures insidethe drum body from impacting the seat, making the seat 23 pressure moreuniform. Finally, separating the seat 23 and the floating seat plate 23provides greater control and ability to manipulate the force between thefloating seat plate and the seat 23 using the spring rates so that theseal is fully loaded by the seat.

In some embodiments the liquid purge media in combination with thefloating seat plate improves the seal between the seat plate 23 and theseat 23 and the seal between the seat plate and the gate 11,particularly as the gate thermally expands and deforms. In someembodiments the seat plate is self-leveling against the gate andcomprises a ball/cone and socket configuration to allow articulation bythe seat. In some embodiments the cone and socket configuration isprovided by the angled shelf 195 and packing 180 at the interfacebetween the seat plate 23 and the seat 23. As the gate 11 or seat 23thermally expand and change shape, the floating seat plate is able toarticulate and maintain a seal independent of the orientation of theseat 23. In some embodiments the spring 165 presses the seat 23 againstthe gate 11 while a bellows 170 is activated by internal pressuring fromthe purge liquid 185 to expand the bellows 170 and assist the springs165 to apply more load on the gate. Any gaps between the seat and seatplate interface are filled with liquid purge medium. The pressurecreated by the increased volume of purge liquid pumped into the chamber175 on the valve side of the bellows adds to the pressure alreadycreated by the bellows to improve the seal between the seat plate 23 andthe gate 11. In some embodiments the liquid purge medium is anincompressible fluid.

In some embodiments the valve comprises a first port 185. In someembodiments the valve comprises a plurality of internal chambers andports 187. In some embodiments ports 187 are in fluid communication withthe valve body so that purge liquid can transport from the valve bodythrough ports 187 to purge liquid chambers 175 comprise channels formedin the seat assembly 145. In some embodiments the operation of thefloating seat plate 23 and the pressurized liquid purge medium protectthe ports 185 from process fluid in the body and which passes throughthe opening 20 as the drum is emptied. In some embodiments two seatplate directly abut seats 23 and gate 11 and prevent process fluid fromentering the gate port 180. In some embodiments the valve compriseslower bonnet plates 34 configured to receive the gate 11 when it isplaced in the closed position. In some embodiments the lower bonnetplates 34 isolate the valve body 14 from the process fluid which maymigrate with the gate 11 as it is moved from a first position to asecond position. In some embodiments the floating seat plate protectsthe port 185 at all times from the inside of the bonnet 30, 33 so whenthe gate 11 hole opens the opening 20 and prevent exposure of the ports185 or the inside of the valve to the process fluid. The ports andchannels 185 running through the valve and bonnet are sized toaccommodate the liquid purge medium.

In some embodiments an isolation valve 14 is configured to isolate avalve body from the process fluid passing through the valve opening 20.In some embodiments a seat 23 has a receiving portion that is configuredto receive a gate. In some embodiments the receiving portion is in themiddle of the seat 23 body. In some embodiments the seat comprises aseat assembly 145 with a seat assembly 145 disposed on opposite sides ofa gate 11 having a first side 12 and a second side 13 and aligned so asto create an opening through which process fluid can selectively pass.In some embodiments the two sides of the seat are bolted together tocreate a seal between the seat and the gate 11. In some placed twoseparate seats which are disposed adjacent the gate 11, with a firstseat 23 adjacent first side 12 of the gate 11 and a second seat 23placed adjacent the second side 13 of the gate 11. In some embodimentsthe gate 11 is configured to be selectively positioned intermediate afirst seat and a second seat.

In some embodiments the seat assembly 145 comprises a floating seatplate. In some embodiments the floating seat plate is nested inside theinner circumference of the seat 23 so as to abut the seat 23. In someembodiments the floating seat plate 23 is concentrically nested betweenthe seat 23 and a valve opening 20 without being attached to the seat23. In some embodiments the seat plate is configured to articulateindependent of the seat 23, to accommodate gate 11 deformations due tothermal expansion or thermal differentials created by greater heat beingapplied to one location over on the surface of the gate 11 such as whenthe heat is applied to the gate's first side 12 and not equally appliedto the gate's second side 13. In addition, in some embodiments thefloating seat plate 23 comprises degrees of motion to accommodatedifferent pressures.

In some embodiments the seat assembly 145 comprises a sealing system 155which improves the seal between the seat plate 23, the seat 23. In someembodiments the sealing system 155 comprises a bias system thatselectively seals the seat plate 23 and the seat 23 that biases the seatplate 23 against the seat 23. In some embodiments the sealing system 155comprises mechanical shapes and packing members 180 which are integratedat the interface between the seat and the seat plate.

In some embodiments the bias system 160 of claim 1 further comprises afirst bias member 165. In some embodiments the bias system comprises afirst bias member 165 and a second bias 170. In some embodiments thebias system comprises a first bias member 165, a second bias member 170,and a third bias member 175. In some embodiments the bias membercomprises a spring 165. In some embodiments the bias member comprises abellows 170. In some embodiments the bias member comprises a purgeliquid chamber 175. In some embodiments the bias system 160 comprisesany combination of bias members which function cooperatively to bias thefloating seat plate 23 against the seat 23. In some embodiments the biassystem functions to bias the floating seat plate 23 against the gate 11.In some embodiments the bias system comprises a plurality of biasmembers configured to bias the floating seat plate 23 against a firstside of the gate 12 and to bias the floating seat plate 23 against thesecond side of the gate 13. In some embodiments the bias system 160further comprises a third bias member positioned on the second side 13of the gate configured to bias the seat plate 23 against the seat 23 ina direction of the gate configured to seal the seat plate 23 and theseat 23 against both the first side 12 and the second side 13 of thegate. In some embodiments the bias system comprises as bias assembly 145limited in travel by a shoulder bolt 199.

In some embodiments the bias system 160 comprising a combination ofcooperatively operating bias members improves the seal to meet AmericanPetroleum Institute (“API”) standards. In some embodiments the floatingseat plate 23 is ground flat and positioned in the center of the gate11. In some embodiments the seat plate 23 is biased against the seatusing springs creating a force of nearly 200 PSI. In some embodiments,in addition to biasing the seat plate 23, the springs give the seatplate 23 degrees of freedom and allows the seat plate 23 to move andadjust so to maintain constant contact with the gate 11 and allows theseat plate 23 to remain in mutual contact with the gate 11 through thethermal cycle. In some embodiments the port 185 further comprises apurge liquid chamber which can be selectively pressurized to expand thechamber and further bias the seat plate 23. The purge medium is pumpedinto the purge liquid chamber and kept under positive pressure to pushpurge liquid through the seals and into the process fluid. The bellows170 is welded 171 to a first packing 180, which in some embodiments is aseat plate 23, and a retainer 173. In some embodiments bellows 170 iswelded 171 to the seat plate 23 and a packing 180 so as to seal thepurge liquid in the purge liquid chamber 175. In some embodiments, purgeliquid is pumped into chamber 175, as the purge liquid volume isincreased the purge liquid chamber 175 expands the bellows 170 expands,increasing the pressure and the seat plate 23 is further biased againstthe seat 23 and the gate 11 to improve the seal between the gate 11 theseat 23 and the seat plate 23. In some embodiments the bias systemcreates a cumulative cooperative force sufficient to meet or exceed theAPI standards of 820 PSI.

In some embodiments the seat plate 23 comprises a shelf 195 whichinterfaces with the seat 23. In some embodiments the shelf 195 is angledto give the seat a conical shape as it mates with the seat 23. In someembodiments packing 180 is inserted into the seat-seat plate interface190 and upon activation the angled shoulder 195 is pressed into the seat23 at the interface 190 and energizes packing 180 by changing the shapeof the packing 180. In some embodiments biasing the seat plate 23against the seat 23 deforms packing 180. In some embodiments, when gate11 deforms, the floating seat plate 23 articulates its position tomaintain the seal between the seat 23 and the seat plate 23 and the gate11 and the seat plate 23. In some embodiments floating seat plate 23adjusts to the changing surface dimensions of the gate 11 as the gate 11repositions from an open position to a closed position or a closedposition to an open position. In some embodiments the packing 180 may becomprise a square cross section with dimensions that are approximatelythe same as the interface 190. In some embodiments the packing 190 willbe slightly larger than the shape of the interface 190. In someembodiments packing 180 will comprise a segment of packing.

In some embodiments packing 180 provides the conically shaped floatingseat plate 23 with freedom of movement to articulate with gate 11thermal expansion as the valve moves through the thermal cycle. In someembodiments the seal is improved by pumping liquid purge medium into thevalve body so the liquid purge medium fills any gaps that may form inthe seal. In some embodiments the packing 180 further improves the sealbetween the seat 23 and the floating seat plate 23 even as the seatplate 23 repositions in response to gate 11 shape changes. In someembodiments the floating seat plate 23 maintains a radially biased forceagainst the packing 180 and seat 23 and the gate 11 even as the shape ofthe gate 11 changes. In some embodiments the floating seat plate 23maintains a radially biased force against the packing 180 and the seat23 and the gate. In some embodiments the seat plate 23 and packing 180isolate the seat 23 from pressure in the body during processing.

In some embodiments packing 180 allows the floating seat plate 23end-to-end movements so gate 11 and floating seat plate 23 and seat 23touch simultaneously. In some embodiments the packing 180 does notnecessarily seal the interface between the seat plate 23 and the seat23, but instead provides for axial movement so the seat plate 23 canbecome mutual with the seat 23. Thus, in some embodiments as the gate 11deforms under thermal expansion the seat plate 23 can repositionindependent of the seat to improve the contact, and thus the sealbetween the seat plate 23 and the gate.

In some embodiments in addition to being welded 171 to the seat plate 23to isolate purge liquid, bellows 170 is cooperatively biased with theseat plate to enhance and improve the sealing force between the seatplate 23, the seat 23 and the gate 11. The bellows 170 is welded 171 tothe seat plate assembly 145 to isolate a purge liquid chamber 175. Insome embodiments the bellows 170 is configured to flex as purge liquidvolume, and resulting pressure is applied to increase the bias force ofthe seat plate assembly 145 against the gate 11. In some embodiments thebellows 170 is made from materials which can be welded. In someembodiments bellows 170 comprises INCONEL®, a nickel chromium-basedsuperalloy or a nickel alloy (e.g. a Monel® alloy). In some embodimentsbellows 170 are configured with a single spring fold 166, while in someembodiments bellows 170 is configured with multiple spring folds 166,the number of folds is determined by the force required and the amountof desired movement. In some embodiments bellows 170 comprises bellowstabs which overlap with adjacent structures. In some embodiments bellowstabs provide a welding surface 171 wherein the bellows tab is welded 171to the adjacent structure. In some embodiments the adjacent structurecomprises the floating seat plate 23. In some embodiments a bellows tabis welded 171 to a packing 180. In some embodiments, the purge liquidchamber 175 is configured on the surface of the bellows 170 which facesaway from the central opening 20, while in some embodiments the purgeliquid chamber 175 is against the bellows surface 175 which facestowards the central opening 175. In some embodiments purge liquid enterspurge liquid chamber 175 through port 185, increasing volume of thepurge liquid chamber 175. In some embodiments the chamber 175 volumeincrease and the purge liquid cooperatively biases other bias memberssuch as spring 165 and bellows 170 to increase the bias force seat plate23 places against the seat 23 and the bias force the seat plate 23exerts against the gate 11 and the force the seat 23 places against thegate 11. In some embodiments bellows 170 is a solid sheet of materialthat is folded and compressed to maintain a bias.

The weld 171 may be formed by any suitable technique including but notlimited to electric arc, laser welding, TIG and electron welding to namea few examples. This weld 62 ensures a fluid tight joint or seal betweenthe bellows 170 and the packing 180 so that fluid flow in the valveopening 20 is restricted to between the first and second ports 36, 38and also that process fluid does not enter into the upper bonnet 30 andlower bonnet 33 actuator 65 or escape to the outside environment.

In some embodiments the valve is configured to continuously force purgeliquid through the port 185 and purge liquid chamber 175. In someembodiments the purge liquid is kept under positive pressure in the tocontinually force purge slurry out of the valve body and into the valveopening 20 to prevent process fluid from entering the bonnets, purgeliquid chamber 175, the port 185, or the valve body 35. In someembodiments the seat plate 180 maintains constant contact and loadagainst the gate 11 to keep sealing surfaces 25 protected. In someembodiments the purge liquid is forced a high pressure through the purgeliquid chamber 175, the port 185, or the valve body 35 purge the spacesof any fluid process which may have entered during the stroke. In someembodiments the seat plate 23 is an extended seat plate 197 thatmaintains constant contact with the gate 11 in all positions through thegate stroke such that all process is captured and not allowed to enterthe body chamber 35.

In some embodiments packing 180, 185 changes shape as floating seatplate 23 presses on packing 180 and radially compresses the packing 180to improve the seal between the seat plate 23 and the seat 23. In someembodiments packing 180 cushions the floating seat plate 180 seat 23interface 190 to permit seat plate 180 to maintain its degrees offreedom under bias, thus even as the gate 11 thermally expands under theheat and pressure of the heat cycle, the floating seat plate 180“floats” or articulates to maintain the seal between the seat plate 180the seat 23 and the gate 11 in a ball/cone and socket manner. In someembodiments the valve comprises two floating seat plates 180 to allowfor sufficient axial seat travel upstream and downstream in the opening20 to balance the sealing load on both sides of the gate 11. In someembodiments the shoulder bolt 199 acts as an axial hard stop on eachseat on each side of the gate 11 allowing the upstream seat 23 tomaintain its sealing contact with the gate 11. A retainer

In some embodiments the extended seat plates 23 on each side of the gate11 prevent the process from entering the body as the valve closes thegate port and exposes the process into the body, typically on otherthrough conduit slab gate valves. In some embodiments extended seatplate 23 are dynamic and spring loaded by the caliper in the bottom ofthe valve. In some embodiments seat plate 23 are further loaded orbiased by a positive pressure purge liquid charge in body cavity 35 whenin operation. In some embodiments the purge liquid is taken fromdownstream where the fluid is pressurized as part of the refiningprocess. In some embodiments a non-pressurized slurry fluid may be takenand pressurized by hydraulic pumps and other known equipment force purgeliquid into the chamber 175 to augment the bellow's force and improvethe seal between the seat plate 23 and the gate 11. In some embodimentsfloating seat plate 23 extends 197 beyond the seat 23. In someembodiments floating seat plate 23 is configured to maintain constantcontact with the gate such that all process fluid is isolated from theseat 23 and prevented from entering the valve body.

In some embodiments the valve may comprise a sealing system 155 whichseals the valve. In some embodiments the sealing system 155 comprises apurge liquid chamber 175. In some embodiments the sealing system 155further comprises packing 180 configured to improve the seal between theseat plate 23 and the seat 23. In some embodiments the sealing system155 comprises the dual dynamic live-loaded floating seating plates whichprovide bi-directional sealing that seals equally with high pressurefrom either flange end of the opening 20.

Some embodiments comprise ports 185, 187 which provides fluidcommunication between the valve body 35 and the purge liquid chamber175. In some embodiments purge liquid passes from the valve body 35through one or both ports 185 or 187 and into the purge liquid chamber175 to bias the floating seat plate 23 against the gate 11 and seat 23.Some embodiments comprise ports 185, 187 formed in the seat 23 at theinterface 190 between the seat 23 and the seat plate 23 and a conicalseat plate 23 comprising an angled shelf 195 which is configured tocreate a radial force into the seat 23 when the seat plate 23 is biasedagainst the seat 23. In some embodiments the port 187 further comprisespacking 180 configured to improve the seal between the seat 23 and theseat plate 23. In some embodiments packing 180 comprises graphite, fiberglass, SPECTRA® fibers or carbon nanofibers, carbon nanotubes, extrudednanotubes or another appropriate material.

In some embodiments isolation valve 14 is configured to isolate at leastone port 185 on a seat plate 23 from a valve opening 20 comprises a gatehaving a first side 12 and a second side 13; a seat 23 furthercomprising: an opening 20; a receiving portion 200 configured to receivea gate, the gate configured to be selectively inserted into thereceiving portion 200 intermediate the seat 23; at least one port 185formed in the seat 23; a conical seat plate 23 nested concentricallyagainst the seat 23 and between the seat 23 and the opening 20 whereinthe seat plate 23 is configured to isolate at least one port 185 formedin the seat 23 from the opening 20 wherein the seat plate 23 if furtherconfigured to articulate independent of the seat 23; and a bias system160 configured to bias the seat plate 23 against the seat 23 to isolatethe seat 23 from the opening 20. In some embodiments the isolation valve14 further comprises packing 180 placed at the interface 190 between theconical seat plate 23 and the seat 23 which packing member 180 deformsas it is compressed radially as the seat plate 23 is biased against theseat 23. In some embodiments the conical seat plate 23 comprises a shelf195 with an angled surface which interface 190 s with the seat 23 and isconfigured to radially compress the packing 180 as the bias system 160is activated. In some embodiments the isolation valve 14 bias system 160comprises a spring 165, a bellows 170 and a purge liquid chamber 175configured to cooperatively work to expand the purge liquid chamber 175and bias the seat plate 23 and seat 23 against the gate 11 when purgeliquid volume of the purge liquid chamber 175 is increased.

Some embodiments teach a method of isolating a purge liquid port fromthe valve opening 20 comprising: providing a gate having a first side 12and a second side 13; providing a seat 23 comprising an opening 20; areceiving portion 200 configured to receive a gate, the gate configuredto be selectively inserted into the receiving portion 200 intermediatethe seat 23; at least one port 185 formed in the seat 23; a conical seatplate 23 nested concentrically against the seat 23 and between the seat23 and the opening 20 wherein the seat plate 23 is configured to isolateat least one port 185 formed in the seat 23 from the opening 20 whereinthe seat plate 23 if further configured to articulate independent of theseat 23; biasing the seat plate 23 against the seat 23 using a biassystem 160; and compressing a packing member 180 placed at the interface190 between the conical seat plate 23 and the seat 23 to substantiallyisolate the at least one port 185 from the opening 20.

In some embodiments the method further comprises providing an angledshelf 195 on the seat plate 23 which shelf 195 interface 190 s with theseat 23 to radially compress the seat 23 as the seat plate 23 is biasedagainst the seat 23. In some embodiments the method further comprisesproviding packing 180 at the shelf 195—seat 23 interface 190 wherein thepacking 180 is configured to be compressed radially upon activation of abias force against the seat plate 23.

In some embodiments the method further comprises selectively biasing theseat plate 23 against the seat 23 by pressurizing the purge liquidchamber 175 with purge liquid. In some embodiments the method furthercomprises isolating the valve body from process fluid with a seat plate23 which extends beyond the seat 23 so that the seat plate 23 scrapesagainst the seat as the gate moves. Some embodiments perform the stepsto the method in a different order, delay performing steps, or eliminatesteps all together.

In closing, it is to be understood that the embodiments of thedisclosure disclosed herein are illustrative of the principles of thepresent disclosure. Other modifications that may be employed are withinthe scope of the disclosure. Thus, by way of example, but not oflimitation, alternative configurations of the present disclosure may beutilized in accordance with the teachings herein. Accordingly, thepresent disclosure is not limited to that precisely as shown anddescribed.

1. An isolation valve liquid-purge system comprising: an isolation valveconfigured to control the flow of process fluid comprising: a gate; ahousing configured to receive the gate; a seat configured to sealagainst the gate; an actuator configured to actuate the gate; andwherein the isolation valve is configured to be purged with a liquidpurge medium.
 2. The system of claim 1, wherein the liquid purge mediumis a hydrocarbon.
 3. The system of claim 2, wherein the hydrocarbonscomprise an LCO.
 4. The system of claim 2, wherein the hydrocarbonscomprise an MCO.
 5. The system of claim 2, wherein the hydrocarbonscomprise an HCO.
 6. The system of claim 1 wherein the purge medium isinjected into the isolation valve under a positive pressure greater thanthe pressure in a line controlled by the isolation valve.
 7. A method ofpurging an isolation valve comprising: distilling oil feedstock intodifferent hydrocarbon weights using a fractionation tower having abottom slurry circuit; controlling the flow of bottom slurry through thebottom slurry circuit with an isolation valve wherein the isolationvalve is purged using liquid purge medium created in the fractionationtower.
 8. The method of claim 7, wherein the liquid purge mediumcomprises hydrocarbons.
 9. The method of claim 6, wherein the liquidpurge medium comprises LCO.
 10. The method of claim 6, wherein theliquid purge medium comprises MCO.
 11. The method of claim 6, whereinthe liquid purge medium comprises HCO.
 12. A method for reducingcavitation in a line comprising: purging an isolation valve controllinga line with process fluid flowing there through with a liquid purgemedium.
 13. The method of claim 12, wherein the purge medium is acomponent of the process fluid.
 14. The method of claim 12, furthercomprising maintaining a positive pressure on the liquid purge mediumgreater than the pressure on the process fluid.